Fix naming issue with Test Summary widget telemetry

What does this MR do and why?

When I did the very first MR widget telemetry rollout, I mistakenly named the non-standard key for the Test Summary widget based on the folder for that widget (test_report).

However, the automated reporting uses the widget name (WidgetTestSummary), so it stopped reporting the legacy event.

This corrects that mistake.

Screenshots or screen recordings

N/A, Redis events.

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